code: def test_single_partition():
      left = cudf.DataFrame({"x": range(200), "y": range(200)})
      right = cudf.DataFrame({"x": range(100), "z": range(100)})
  
      dleft = dd.from_pandas(left, npartitions=1)
      dright = dd.from_pandas(right, npartitions=10)
  
      m = dleft.merge(dright, how="inner")
      assert len(m.dask) < len(dleft.dask) + len(dright.dask) * 3
  
      dleft = dd.from_pandas(left, npartitions=5)
      m2 = dleft.merge(right, how="inner")
      assert len(m2.dask) < len(dleft.dask) * 3
      assert len(m2) == 100
  
file_path: cudf/python/dask_cudf/dask_cudf/tests/test_join.py
imports: from functools import partial
  import numpy
  import pandas
  import pytest
  from dask import dataframe
  import cudf
  import dask_cudf
label_desc: Use image node_id 10 for calling a global function with example usage: test_single_partition() without return types